U.S. patent number 10,524,907 [Application Number 16/149,969] was granted by the patent office on 2020-01-07 for expandable sheath for introducing an endovascular delivery device into a body.
This patent grant is currently assigned to Edwards Lifesciences Corporation. The grantee listed for this patent is EDWARDS LIFESCIENCES CORPORATION. Invention is credited to Duy Nguyen, Kim D. Nguyen, Thanh V. Nguyen.
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United States Patent |
10,524,907 |
Nguyen , et al. |
January 7, 2020 |
Expandable sheath for introducing an endovascular delivery device
into a body
Abstract
Embodiments of an expandable sheath can be used in conjunction
with a catheter assembly to introduce a prosthetic device, such as
a heart valve, into a patient. Such embodiments can minimize trauma
to the vessel by allowing for temporary expansion of a portion of
the introducer sheath to accommodate the delivery apparatus,
followed by a return to the original diameter once the prosthetic
device passes through. Some embodiments can include a sheath with
inner and outer layers, where a folded portion of the inner layer
extends through a slit in the outer layer and a portion of the
outer layer overlaps the folded portion of the inner layer. Some
embodiments include an elastic outer cover positioned outside the
outer layer. Embodiments of the present expandable sheath can avoid
the need for multiple insertions for the dilation of the vessel,
thus offering advantages over prior art introducer sheaths.
Inventors: |
Nguyen; Duy (Corona, CA),
Nguyen; Kim D. (Irvine, CA), Nguyen; Thanh V. (Irvine,
CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
EDWARDS LIFESCIENCES CORPORATION |
Irvine |
CA |
US |
|
|
Assignee: |
Edwards Lifesciences
Corporation (Irvine, CA)
|
Family
ID: |
45890464 |
Appl.
No.: |
16/149,969 |
Filed: |
October 2, 2018 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190029824 A1 |
Jan 31, 2019 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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15997587 |
Jun 4, 2018 |
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15057953 |
Jun 5, 2018 |
9987134 |
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14324894 |
Apr 5, 2016 |
9301841 |
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13312739 |
Jul 29, 2014 |
8790387 |
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12249867 |
Apr 8, 2014 |
8690936 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F
2/2436 (20130101); A61F 2/2427 (20130101); A61F
2/2418 (20130101); A61F 2/2433 (20130101); A61B
90/39 (20160201); Y10T 156/1026 (20150115) |
Current International
Class: |
A61F
2/24 (20060101); A61B 90/00 (20160101) |
References Cited
[Referenced By]
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Other References
510K Premarket Notification, Jun. 22, 2018. cited by applicant
.
BSX Structural Heart Update 2018, Feb. 2018. cited by applicant
.
Related U.S. Appl. No. 14/880,111 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 16/036,190 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 16/149,947 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 14/324,894 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 14/312,739 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 12/249,867 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 15/057,953 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 16/149,953 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 16/149,956 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 16/149,960 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 14/880,109 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 16/149,636 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 16/149,650 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 16/149,671 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 16/149,683 and the file history thereof.
cited by applicant .
Related U.S. Appl. No. 16/149,697 and the file history thereof.
cited by applicant.
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Primary Examiner: Stransky; Katrina M
Attorney, Agent or Firm: Meunier Carlin & Curfman LLC
German; Joel B.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
The present application is a continuation of U.S. patent
application Ser. No. 15/997,587, filed Jun. 4, 2018, which is a
continuation of U.S. patent application Ser. No. 15/057,953, filed
Mar. 1, 2016, now U.S. Pat. No. 9,987,134, which is a continuation
of U.S. patent application Ser. No. 14/324,894, filed Jul. 7, 2014,
now U.S. Pat. No. 9,301,841, which is a continuation of U.S. patent
application Ser. No. 13/312,739, filed Dec. 6, 2011, now U.S. Pat.
No. 8,790,387, which is a continuation-in-part of U.S. patent
application Ser. No. 12/249,867, filed Oct. 10, 2008, now U.S. Pat.
No. 8,690,936. Each of these applications are hereby incorporated
by reference herein in their entirety and for all purposes.
Claims
We claim:
1. A method of delivering a medical device through a sheath, the
method comprising: introducing the medical device into a proximal
end of an elongate lumen defined by an inner layer of the sheath;
advancing the medical device through the lumen along an axis of the
lumen and toward a distal end of the lumen; and locally expanding
the lumen of the sheath at a local axial location while advancing
the medical device through the local axial location, wherein
locally expanding the lumen comprises: moving a first fold of the
inner layer circumferentially closer to a second fold of the inner
layer and shortening an overlapping portion of the inner layer
extending circumferentially between the first and second folds; and
expanding an outer layer along at least one elongate gap generally
aligned with the axis of the lumen and positioned adjacent to at
least one of the folds, wherein expanding the outer layer along at
least one elongate gap comprises moving a first portion of the
outer layer away from a second portion of the outer layer such that
the gap is defined between the first and second portions, as the
first fold moves closer to the second fold, wherein the outer layer
extending between the first and second portions remains in place
over the inner layer during expansion.
2. The method of claim 1, wherein expanding the outer layer along
at least one gap further comprises expanding the gap over the
overlapping portion.
3. The method of claim 2, further comprising expanding the inner
layer into the gap.
4. The method of claim 3, further comprising expanding the inner
layer into a substantially cylindrical tube.
5. The method of claim 1, further comprising expanding the outer
layer along a plurality of substantially equally circumferentially
spaced gaps.
6. The method of claim 1, further comprising merging the first and
second folds and eliminating the overlapping portion at the local
axial location.
7. The method of claim 6, further comprising expanding the inner
layer at the local axial location into a substantially tubular,
unfolded cross-section.
8. The method of claim 7, further comprising contracting the inner
layer after passage of the medical device.
9. The method of claim 1, further comprising exerting a radial
force on the gap of the outer layer and widening the outer layer
along the gap.
10. The method of claim 9, further comprising moving one of the
folds closer to the gap during application of the radial force.
11. The method of claim 1, further comprising moving a third fold
of the inner layer toward a fourth fold of the inner layer and
shortening an overlapping portion of the inner layer extending
circumferentially between the third fold and the fourth fold, the
third and fourth fold circumferentially spaced from the first and
second folds.
12. The method of claim 1, wherein the gap is adjacent the first
fold and further comprising passing the first fold radially under
the gap as the first fold moves closer to the second fold.
13. The method of claim 1, wherein introducing the medical device
comprises introducing a stent-mounted heart valve into the proximal
end of the lumen and further comprising extending the soft-tissue
heart valve out of the distal end of the elongate lumen.
14. The method of claim 13, further comprising expanding the
stent-mounted heart valve after it exits the elongate lumen.
15. The method of claim 1, further comprising radially spacing the
overlapping portion from an outer surface of a non-overlapping
portion of the inner layer.
16. The method of claim 1, further comprising using a stiffness of
the outer layer for introducing the sheath into a patient
anatomy.
17. The method of claim 1, further comprising moving the first fold
of the inner layer circumferentially closer to a third fold of the
inner layer.
18. The method of claim 17, wherein a second overlapping portion of
the inner layer extends circumferentially between the third and
second folds, wherein the second overlapping portion extends over
the second fold.
19. The method of claim 18, wherein the folds are folded regions.
Description
FIELD
The present application concerns embodiments of a sheath for use
with catheter-based technologies for repairing and/or replacing
heart valves, as well as for delivering a prosthetic device, such
as a prosthetic valve to a heart via the patient's vasculature.
BACKGROUND
Endovascular delivery catheter assemblies are used to implant
prosthetic devices, such as a prosthetic valve, at locations inside
the body that are not readily accessible by surgery or where access
without invasive surgery is desirable. For example, aortic, mitral,
tricuspid, and/or pulmonary prosthetic valves can be delivered to a
treatment site using minimally invasive surgical techniques.
An introducer sheath can be used to safely introduce a delivery
apparatus into a patient's vasculature (e.g., the femoral artery).
An introducer sheath generally has an elongated sleeve that is
inserted into the vasculature and a housing that contains one or
more sealing valves that allow a delivery apparatus to be placed in
fluid communication with the vasculature with minimal blood loss. A
conventional introducer sheath typically requires a tubular loader
to be inserted through the seals in the housing to provide an
unobstructed path through the housing for a valve mounted on a
balloon catheter. A conventional loader extends from the proximal
end of the introducer sheath, and therefore decreases the available
working length of the delivery apparatus that can be inserted
through the sheath and into the body.
Conventional methods of accessing a vessel, such as a femoral
artery, prior to introducing the delivery system include dilating
the vessel using multiple dilators or sheaths that progressively
increase in diameter. This repeated insertion and vessel dilation
can increase the amount of time the procedure takes, as well as the
risk of damage to the vessel.
Radially expanding intravascular sheaths have been disclosed. Such
sheaths tend to have complex mechanisms, such as ratcheting
mechanisms that maintain the shaft or sheath in an expanded
configuration once a device with a larger diameter than the
sheath's original diameter is introduced.
However, delivery and/or removal of prosthetic devices and other
material to or from a patient still poses a significant risk to the
patient. Furthermore, accessing the vessel remains a challenge due
to the relatively large profile of the delivery system that can
cause longitudinal and radial tearing of the vessel during
insertion. The delivery system can additionally dislodge calcified
plaque within the vessels, posing an additional risk of clots
caused by the dislodged plaque.
Accordingly, there remains a need in the art for an improved
introducer sheath for endovascular systems used for implanting
valves and other prosthetic devices.
SUMMARY
Embodiments of the present expandable sheath can minimize trauma to
the vessel by allowing for temporary expansion of a portion of the
introducer sheath to accommodate a delivery system, followed by a
return to the original diameter once the delivery system passes
through. Some embodiments can comprise a sheath with a smaller
profile than that of prior art introducer sheaths. Furthermore,
certain embodiments can reduce the length of time a procedure
takes, as well as reduce the risk of a longitudinal or radial
vessel tear, or plaque dislodgement because only one sheath is
required, rather than several different sizes of sheaths.
Embodiments of the present expandable sheath can require only a
single vessel insertion, as opposed to requiring multiple
insertions for the dilation of the vessel.
One embodiment of a sheath for introducing a prosthetic device
comprises an inner layer and an outer layer. At least a portion of
the sheath can be designed or configured to locally expand from a
first diameter to a second diameter as the prosthetic device is
pushed through a lumen of the sheath, and then at least partially
return to the first diameter once the prosthetic device has passed
through. Some embodiments can additionally include an elastic outer
cover disposed about the outer layer.
The inner layer can comprise polytetrafluoroethylene (PTFE),
polyimide, polyetheretherketone (PEEK), polyurethane, nylon,
polyethylene, polyamide, or combinations thereof. The outer layer
can comprise PTFE, polyimide, PEEK, polyurethane, nylon,
polyethylene, polyamide, polyether block amides, polyether block
ester copolymer, thermoset silicone, latex, poly-isoprene rubbers,
high density polyethylene (HDPE), Tecoflex, or combinations
thereof. In one exemplary embodiment, the inner layer can comprise
PTFE and the outer layer can comprise a combination of HDPE and
Tecoflex. If present, the elastic outer cover can include any
suitable materials, such as any suitable heat shrink materials.
Examples include Pebax, polyurethane, silicone, and/or
polyisoprene.
Disclosed embodiments of a sheath comprise a proximal end and a
distal end opposite one another. Some embodiments can include a
hemostasis valve at or near the proximal end of the sheath. In some
embodiments, the outer diameter of the sheath decreases along a
gradient from the proximal end to the distal end of the sheath. In
other embodiments, the outer diameter of the sheath is
substantially constant along at least a majority of the length of
the sheath.
One embodiment of a sheath for introducing a prosthetic device into
a body can comprise a continuous inner layer defining a lumen
therethrough, the inner layer having a folded portion and a
discontinuous outer layer having an overlapping portion and an
underlying portion. In some embodiments, the inner layer can have
at least two folded portions. The outer layer can be configured so
that the overlapping portion overlaps the underlying portion,
wherein at least a portion of the folded portion of the inner
tubular layer is positioned between the overlapping and underlying
portions. At least a portion of the sheath is configured to expand
to accommodate the prosthetic device.
In some embodiments, at least a portion of the sheath is configured
such that a plurality of segments of the sheath each locally
expands one at a time from a rest configuration having a first
diameter to an expanded configuration having a second diameter that
is larger than the first diameter to facilitate passage of the
prosthetic device through the lumen of the inner layer. Each
segment can have a length defined along the longitudinal axis of
the sheath, and each segment of the sheath can be configured to at
least partially return to the first diameter once the prosthetic
device has passed through. In some embodiments, when each segment
of the sheath is in the expanded configuration, a length of the
folded portion corresponding to the length of the segment at least
partially unfolds (e.g., by separating and/or straightening). A
length of the overlapping portion corresponding to the length of
the segment can be configured to move with respect to the
underlying portion when each segment of the sheath expands from the
rest configuration to the expanded configuration.
In one specific embodiment, the inner layer comprises PTFE and the
outer layer comprises HDPE and/or Tecoflex. The inner and outer
layers can be thermally fused together in some embodiments. In some
embodiments, the inner layer comprises a woven fabric and/or
braided filaments such as yarn filaments of PTFE, PET, PEEK, and/or
nylon.
Some disclosed expandable sheaths can further include an elastic
outer cover disposed on an external surface of the outer layer. The
elastic outer cover can comprise, for example, heat shrink tubing.
Some sheaths include one or more radiopaque marker or fillers, such
as a C-shaped band positioned between the inner and outer layers
near the distal end of the sheath. Some embodiments include a soft
tip secured to the distal end of the sheath.
In some embodiments, the inner layer can include at least one
folded portion and at least one weakened portion. A discontinuous
outer layer can have an outer surface and an inner surface and a
longitudinal gap, and a portion of the inner layer can extend
through the longitudinal gap. The at least one folded portion of
the inner layer can be positioned adjacent a portion of the outer
surface of the outer layer. In some embodiments, the weakened
portion can comprise a score line along at least a portion of the
inner layer and/or a slit along at least a portion of the inner
layer. The weakened portion can be positioned at the at least one
folded portion of the inner layer. In some embodiments, the
longitudinal gap can be positioned between a first end and a second
end of the outer layer.
In some embodiments, an expandable sheath can include a hydrophilic
inner liner defining a generally horseshoe-shaped lumen
therethrough, the inner liner including at least two weakened
portions and an elastic cover positioned radially outward of the
inner liner. In some embodiments, when the sheath is in the
expanded configuration, the inner liner splits apart at the
weakened portions so as to form a discontinuous inner liner.
Methods of making a sheath are also disclosed. One method includes
providing a mandrel having a first diameter, providing a first tube
having a second diameter, the second diameter being larger than the
first diameter, mounting the first tube on the mandrel, gathering
excess material of the first tube and folding the excess material
to one side to form a folded portion of the inner layer. A second
tube can then be provided, and the second tube can be cut to form a
coiled layer. An adhesive can be applied to at least a portion of
the coiled layer and the coiled layer can be mounted on the first
tube such that the adhesive is positioned between the first tube
and the coiled layer. The folded portion can be lifted in order to
position a portion of the coiled layer under the folded
portion.
Some methods include applying heat to the first tube, coiled layer,
and mandrel so as to thermally fuse the first tube and the coiled
layer together. In some methods, an elastic outer cover can be
secured to the outer surface of the coiled layer. In some methods,
a soft tip portion can be coupled to a distal end of the expandable
sheath to facilitate passing the expandable sheath through a
patient's vasculature.
The foregoing and other features and advantages of the invention
will become more apparent from the following detailed description,
which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevation view of a sheath according to the present
disclosure along with an endovascular delivery apparatus for
implanting a prosthetic valve.
FIGS. 2A, B, and D are section views of embodiments of a sheath for
introducing a prosthetic device into a patient, and FIG. 2C is a
perspective view of one component of such a sheath.
FIG. 3 is an elevation view of the sheath shown in FIG. 2.
FIGS. 4A-4B are elevation views of two embodiments of a sheath
according to the present disclosure, having varying outer
diameters.
FIG. 5 illustrates an elevation view of one embodiment of a sheath,
expanded at a first location to accommodate a delivery system.
FIG. 6 shows an elevation view of the sheath of claim 5, expanded
at a second location, farther down the sheath.
FIG. 7 shows a section view of another embodiment of a sheath that
further comprises an outer covering or shell.
FIG. 8 illustrates an elevation view of one embodiment of a sheath
with an outer covering or shell.
FIG. 9 illustrates a partial elevation view of one embodiment of an
intermediate tubular layer that can be used to construct a sheath
according to the present disclosure.
FIG. 10 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a variable diamond
design.
FIG. 11 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a diamond design with
spring struts.
FIG. 12 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a diamond design with
straight struts.
FIG. 13 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a saw tooth design with
spring struts.
FIG. 14 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a saw tooth design with
straight struts.
FIG. 15 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a diamond design with
straight struts.
FIG. 16 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a helical or spiral
design.
FIG. 17 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a diamond design with
non-straight struts.
FIG. 18 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having an alternative diamond
design with non-straight struts.
FIG. 19 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having yet another diamond design
with non-straight struts.
FIG. 20 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a diamond design with
struts.
FIG. 21 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a design similar to that
shown in FIG. 20, but with additional struts.
FIG. 22 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a diamond design with
spiral struts.
FIG. 23 illustrates a partial elevation view of another embodiment
of an intermediate tubular layer having a diamond design with
adjacent struts.
FIG. 24 illustrates a section view of one embodiment of a sheath
having a longitudinal notch.
FIG. 25 shows a section view of one embodiment of a sheath having a
longitudinal cut in the inner layer.
FIG. 26 shows a perspective view of one embodiment of a sheath
having a plurality of notches or cuts in the outer tubular
layer.
FIG. 27A illustrates a section view of one embodiment of a sheath,
wherein the outer tubular layer contains a longitudinal cut, and
the inner layer extends into the gap created by the cut in the
outer tubular layer, in an unexpanded configuration; and FIGS.
27B-27E show section views of various embodiments of a sheath in
the unexpanded configuration.
FIG. 28 shows a section view of the sheath of FIG. 27A in an
expanded configuration.
FIGS. 29A-29D show section views of various embodiments of a sheath
having overlapping sections.
FIG. 30 illustrates a block diagram of one embodiment of a method
of making a sheath according to the present disclosure.
FIG. 31 illustrates a block diagram of another embodiment of a
method of making a sheath according to the present disclosure.
FIGS. 32A-32H illustrates section or elevation views of various
method steps of the methods shown in FIGS. 30-31.
FIG. 33 illustrates a plan view of one embodiment of a sheath
having a partial slit or score line.
FIG. 34 illustrates a plan view of another embodiment of a sheath
having a partial slit or score line.
FIG. 35 is an elevation view of an expandable sheath according to
the present disclosure and a representative housing.
FIG. 36 is an enlarged cutaway view of the distal end of the sheath
of FIG. 35.
FIG. 37 is a section view of the distal end of the sheath of FIG.
35, taken along line 37-37 in FIG. 36.
FIG. 38 is a section view of a proximal section of the sheath of
FIG. 35, taken along line 38-38 in FIG. 35.
FIG. 39 is a section view of the sheath of FIG. 35 in a rest
(unexpanded) configuration, taken along line 39-39 in FIG. 35.
FIG. 40 is the section view of the sheath of FIG. 39, in an
expanded configuration.
FIG. 41 shows an elevation view of an expandable sheath having an
elastic outer cover, according to another embodiment.
FIG. 42 illustrates a section view of the sheath of FIG. 41, taken
along line 42-42 in FIG. 41.
FIG. 43 illustrates the section view of the sheath shown in FIG.
42, in an expanded configuration.
FIG. 44 illustrates a section view of another embodiment of an
expandable sheath.
FIG. 45 shows an expanded configuration of the sheath of FIG.
44.
FIG. 46 illustrates a section view of another embodiment of an
expandable sheath.
FIG. 47 shows an expanded configuration of the sheath of FIG.
46.
FIG. 48 illustrates a section view of another embodiment of an
expandable sheath according to the present disclosure.
FIG. 49 illustrates a section view of another embodiment of an
expandable sheath.
DETAILED DESCRIPTION
As used in this application and in the claims, the singular forms
"a," "an," and "the" include the plural forms unless the context
clearly dictates otherwise. Additionally, the term "includes" means
"comprises." Further, the terms "coupled" and "associated"
generally means electrically, electromagnetically, and/or
physically (e.g., mechanically or chemically) coupled or linked and
does not exclude the presence of intermediate elements between the
coupled or associated items.
Although the operations of exemplary embodiments of the disclosed
method may be described in a particular, sequential order for
convenient presentation, it should be understood that disclosed
embodiments can encompass an order of operations other than the
particular, sequential order disclosed. For example, operations
described sequentially may in some cases be rearranged or performed
concurrently. Further, descriptions and disclosures provided in
association with one particular embodiment are not limited to that
embodiment, and may be applied to any embodiment disclosed.
Moreover, for the sake of simplicity, the attached figures may not
show the various ways (readily discernable, based on this
disclosure, by one of ordinary skill in the art) in which the
disclosed system, method, and apparatus can be used in combination
with other systems, methods, and apparatuses. Additionally, the
description sometimes uses terms such as "produce" and "provide" to
describe the disclosed method. These terms are high-level
abstractions of the actual operations that can be performed. The
actual operations that correspond to these terms can vary depending
on the particular implementation and are, based on this disclosure,
readily discernible by one of ordinary skill in the art.
Disclosed embodiments of an expandable sheath can minimize trauma
to the vessel by allowing for temporary expansion of a portion of
the introducer sheath to accommodate the delivery system, followed
by a return to the original diameter once the device passes
through. Some embodiments can comprise a sheath with a smaller
profile (e.g., a smaller diameter in the rest configuration) than
that of prior art introducer sheaths. Furthermore, present
embodiments can reduce the length of time a procedure takes, as
well as reduce the risk of a longitudinal or radial vessel tear, or
plaque dislodgement because only one sheath is required, rather
than several different sizes of sheaths. Embodiments of the present
expandable sheath can avoid the need for multiple insertions for
the dilation of the vessel. Such expandable sheaths can be useful
for many types of minimally invasive surgery, such as any surgery
requiring introduction of an apparatus into a subject's vessel. For
example, the sheath can be used to introduce other types of
delivery apparatus for placing various types of intraluminal
devices (e.g., stents, prosthetic heart valves, stented grafts,
etc.) into many types of vascular and non-vascular body lumens
(e.g., veins, arteries, esophagus, ducts of the biliary tree,
intestine, urethra, fallopian tube, other endocrine or exocrine
ducts, etc.).
FIG. 1 illustrates a sheath 8 according to the present disclosure,
in use with a representative delivery apparatus 10, for delivering
a prosthetic device 12, such as a tissue heart valve to a patient.
The apparatus 10 can include a steerable guide catheter 14 (also
referred to as a flex catheter), a balloon catheter 16 extending
through the guide catheter 14, and a nose catheter 18 extending
through the balloon catheter 16. The guide catheter 14, the balloon
catheter 16, and the nose catheter 18 in the illustrated embodiment
are adapted to slide longitudinally relative to each other to
facilitate delivery and positioning of the valve 12 at an
implantation site in a patient's body, as described in detail
below. Generally, sheath 8 is inserted into a vessel, such as the
transfemoral vessel, passing through the skin of patient, such that
the distal end of the sheath 8 is inserted into the vessel. Sheath
8 can include a hemostasis valve at the opposite, proximal end of
the sheath. The delivery apparatus 10 can be inserted into the
sheath 8, and the prosthetic device 12 can then be delivered and
implanted within patient.
FIGS. 2A, 2B, and 2D show section views of embodiments of a sheath
22 for use with a delivery apparatus such as that shown in FIG. 1.
FIG. 2C shows a perspective view of one embodiment of an inner
layer 24 for use with the sheath 22. Sheath 22 includes an inner
layer, such as inner polymeric tubular layer 24, an outer layer,
such as outer polymeric tubular layer 26, and an intermediate
tubular layer 28 disposed between the inner and outer polymeric
tubular layers 24, 26. The sheath 22 defines a lumen 30 through
which a delivery apparatus can travel into a patient's vessel in
order to deliver, remove, repair, and/or replace a prosthetic
device. Such introducer sheaths 22 can also be useful for other
types of minimally invasive surgery, such as any surgery requiring
introduction of an apparatus into a subject's vessel. For example,
the sheath 22 also can be used to introduce other types of delivery
apparatus for placing various types of intraluminal devices (e.g.,
stents, stented grafts, etc.) into many types of vascular and
non-vascular body lumens (e.g., veins, arteries, esophagus, ducts
of the biliary tree, intestine, urethra, fallopian tube, other
endocrine or exocrine ducts, etc.).
The outer polymeric tubular layer 26 and the inner polymeric
tubular layer 24 can comprise, for example, PTFE (e.g.
Teflon.RTM.), polyimide, PEEK, polyurethane, nylon, polyethylene,
polyamide, polyether block amides (e.g. PEBAX.RTM.), polyether
block ester copolymer, polyesters, fluoropolymers, polyvinyl
chloride, thermoset silicone, latex, poly-isoprene rubbers,
polyolefin, other medical grade polymers, or combinations thereof.
The intermediate tubular layer 28 can comprise a shape memory alloy
such as Nitinol, and/or stainless steel, cobalt chromium, spectra
fiber, polyethylene fiber, aramid fiber, or combinations
thereof.
The inner polymeric tubular layer 24 can advantageously be provided
with a low coefficient of friction on its inner surface. For
example, the inner polymeric tubular layer 24 can have a
coefficient of friction of less than about 0.1. Some embodiments of
a sheath 22 can include a lubricious liner on the inner surface 32
of the inner polymeric tubular layer 24. Such a liner can
facilitate passage of a delivery apparatus through the lumen 30 of
the sheath 22. Examples of suitable lubricious liners include
materials that can reduce the coefficient of friction of the inner
polymeric tubular layer 24, such as PTFE, polyethylene,
polyvinylidine fluoride, and combinations thereof. Suitable
materials for a lubricious liner also include other materials
desirably having a coefficient of friction of about 0.1 or
less.
The inner diameter of the intermediate tubular layer 28 varies
depending on the application and size of the delivery apparatus and
prosthetic device. In some embodiments, the inner diameter ranges
from about 0.005 inches to about 0.400 inches. The thickness of the
intermediate tubular layer 28 can be varied depending on the
desired amount of radial expansion, as well as the strength
required. For example, the thickness of the intermediate tubular
layer 28 can be from about 0.002 inches to about 0.025 inches. The
thicknesses of the inner polymeric tubular layer 24 and the outer
polymeric tubular layer 26 can also be varied depending on the
particular application of the sheath 22. In some embodiments, the
thickness of the inner polymeric tubular layer 24 ranges from about
0.0005 inches to about 0.010 inches, and in one particular
embodiment, the thickness is about 0.002 inches. Outer polymeric
tubular layers 26 can have a thickness of from about 0.002 inches
to about 0.015 inches, and in one particular embodiment the outer
polymeric tubular layer 26 has a thickness of about 0.010
inches.
The hardness of each layer of the sheath 22 can also be varied
depending on the particular application and desired properties of
the sheath 22. In some embodiments, the outer polymeric tubular
layer 26 has a Shore hardness of from about 25 Durometer to about
75 Durometer.
Additionally, some embodiments of a sheath 22 can include an
exterior hydrophilic coating on the outer surface 34 of the outer
polymeric tubular layer 26. Such a hydrophilic coating can
facilitate insertion of the sheath 22 into a patient's vessel.
Examples of suitable hydrophilic coatings include the Harmony.TM.
Advanced Lubricity Coatings and other Advanced Hydrophilic Coatings
available from SurModics, Inc., Eden Prairie, Minn. DSM medical
coatings (available from Koninklijke DSM N.V, Heerlen, the
Netherlands), as well as other hydrophilic coatings, are also
suitable for use with the sheath 22.
In some embodiments, the outer surface 34 of the outer polymeric
tubular layer 26 can be modified. For example, surface
modifications such as plasma etching can be performed on the outer
surface 34. Similarly, other surfaces, both outer and inner, can be
surface modified according to certain embodiments and desired
application. In some embodiments, surface modification can improve
adhesion between the layers in the areas of the modification.
The sheath 22 also can have at least one radiopaque filler or
marker. The radiopaque filler or marker can be associated with the
outer surface 34 of the outer polymeric tubular layer 26.
Alternatively, the radiopaque filler or marker can be embedded or
blended within the outer polymeric tubular layer 24. Similarly, the
radiopaque filler or marker can be associated with a surface of the
inner polymeric tubular layer 24 or the intermediate tubular layer
28 or embedded within either or both of those layers.
Suitable materials for use as a radiopaque filler or marker
include, for example, barium sulfite, bismuth trioxide, titanium
dioxide, bismuth subcarbonate, or combinations thereof. The
radiopaque filler can be mixed with or embedded in the material
used to form the outer polymeric tubular layer 26, and can comprise
from about 5% to about 45% by weight of the outer polymeric tubular
layer. More or less radiopaque material can be used in some
embodiments, depending on the particular application.
In some embodiments, the inner polymeric tubular layer 24 can
comprise a substantially uniform cylindrical tube. In alternative
embodiments, the inner polymeric tubular layer 24 can have at least
one section of discontinuity along its longitudinal axis to
facilitate radial expansion of the inner polymeric tubular layer
24. For example, the inner polymeric tubular layer 24 can be
provided with one or more longitudinal notches and/or cuts 36
extending along at least a portion of the length of the sheath 22.
Such notches or cuts 36 can facilitate radial expansion of the
inner polymeric tubular layer 24, thus accommodating passage of a
delivery apparatus or other device. Such notches and/or cuts 36 can
be provided near the inner surface 32, near the outer surface 37,
and/or substantially through the entire thickness of the inner
polymeric layer 24. In embodiments with a plurality of notches
and/or cuts 36, such notches and/or cuts 36 can be positioned such
that they are substantially equally spaced from one another
circumferentially around the inner polymeric layer 24.
Alternatively, notches and cuts 36 can be spaced randomly in
relation to one another, or in any other desired pattern. Some or
all of any provided notches and/or cuts 36 can extend
longitudinally along substantially the entire length of the sheath
22. Alternatively, some or all of any provided notches and/or cuts
36 can extend longitudinally only along a portion of the length of
the sheath 22.
As shown in FIGS. 2B and 2C (which illustrates only the inner
polymeric tubular layer 24), in some embodiments, the inner
polymeric tubular layer 24 contains at least one notch or cut 36
that extends longitudinally and parallel to an axis defined by the
lumen 30, extending substantially the entire length of the sheath
22. Thus, upon introduction of a delivery apparatus, the inner
polymeric tubular layer 24 can split open along the notch and/or
cut 36 and expand, thus accommodating the delivery apparatus.
Additionally or alternatively, as shown in FIG. 2D, the outer
polymeric tubular layer 26 can comprise one or more notches and/or
cuts 36. Notches and/or cuts 36, in some embodiments, do not extend
through the entire thickness of the outer tubular layer 26. The
notches and/or cuts 36 can be separable upon radial expansion of
the sheath 22. The outer polymeric tubular layer 26 can be
retractable longitudinally, or able to be pulled back away from the
intermediate tubular layer 28 and the inner polymeric tubular layer
24. In embodiments with a retractable outer polymeric tubular layer
26, the outer polymeric tubular layer 26 can be retracted to
accommodate or facilitate passage of a delivery apparatus through
the lumen 30, and then can be replaced to its original position on
the sheath 22.
FIG. 3 illustrates an elevation view of the sheath 22 shown in FIG.
2A. In this view, only the outer polymeric tubular layer 26 is
visible. The sheath 22 comprises a proximal end 38 and a distal end
40 opposite the proximal end 38. The sheath 22 can include a
hemostasis valve inside the lumen of the sheath 22, at or near the
proximal end 38 of the sheath 22. Additionally, the sheath 22 can
comprise a soft tip 42 at the distal end 40 of the sheath 22. Such
a soft tip 42 can be provided with a lower hardness than the other
portions of the sheath 22. In some embodiments, the soft tip 42 can
have a Shore hardness from about 25 D to about 40 D.
As shown in FIG. 3, the unexpanded original outer diameter of the
sheath 22 can be substantially constant across the length of the
sheath 22, substantially from the proximal end 38 to the distal end
40. In alternative embodiments, such as the ones illustrated in
FIGS. 4A-4B, the original unexpanded outer diameter of the sheath
22 can decrease from the proximal end 38 to the distal end 40. As
shown in the embodiment in FIG. 4A, the original unexpanded outer
diameter can decrease along a gradient, from the proximal end 38 to
the distal end 40. In alternative embodiments, such as the one
shown in FIG. 4B, the original unexpanded outer diameter of sheath
22 can incrementally step down along the length of the sheath 22,
wherein the largest original unexpanded outer diameter is near the
proximal end 38 and the smallest original unexpanded outer diameter
is near the distal end 40 of the sheath 22.
As shown in FIGS. 5-6, the sheath 22 can be designed to locally
expand as the prosthetic device is passed through the lumen of the
sheath 22, and then substantially return to its original shape once
the prosthetic device has passed through that portion of the sheath
22. For example, FIG. 5 illustrates a sheath 22 have a localized
bulge 44, representative of a device being passed through the
internal lumen of the sheath 22. FIG. 5 shows the device close to
the proximal end 38 of the sheath 22, close to the area where the
device is introduced into the sheath 22. FIG. 6 shows the sheath 22
of FIG. 5, with the device having progressed further along the
sheath 22. The localized bulge 44 is now closer to the distal end
40 of the sheath 22, and thus is about to be introduced to a
patient's vessel. As evident from FIGS. 5 and 6, once the localized
bulge associated with the device has passed through a portion of
the lumen of the sheath 22, that portion of the sheath 22 can
automatically return to its original shape and size, at least in
part due to the materials and structure of the sheath 22.
The sheath 22 has an unexpanded inner diameter equal to the inner
diameter of the inner polymeric tubular layer (not visible in FIGS.
5-6), and an unexpanded outer diameter 46 equal to the outer
diameter of the outer polymeric tubular layer 26. The sheath 22 is
designed to be expanded to an expanded inner diameter and an
expanded outer diameter 48 which are larger than the unexpanded
inner diameter and the unexpanded outer diameter 46, respectively.
In one representative embodiment, the unexpanded inner diameter is
about 16 Fr and the unexpanded outer diameter 46 is about 19 Fr,
while the expanded inner diameter is about 26 Fr and the expanded
outer diameter 48 is about 29 Fr. Different sheaths 22 can be
provided with different expanded and unexpanded inner and outer
diameters, depending on the size requirements of the delivery
apparatus for various applications. Additionally, some embodiments
can provide more or less expansion depending on the particular
design parameters, the materials, and/or configurations used.
In some embodiments of a sheath according to the present
disclosure, and as shown in section in FIG. 7 and in elevation in
FIG. 8, the sheath 22 can additionally comprise an outer covering,
such as outer polymeric covering 50, disposed on the outer surface
52 of the outer polymeric tubular layer 26. The outer polymeric
covering 50 can provide a protective covering for the underlying
sheath 22. In some embodiments, the outer polymeric covering 50 can
contain a self-expandable sheath in a crimped or constrained state,
and then release the self-expandable sheath upon removal of the
outer polymeric covering 50. For example, in some embodiments of a
self-expandable sheath, the intermediate layer 28 can comprise
Nitinol and/or other shape memory alloys, and the intermediate
layer 28 can be crimped or radially compressed to a reduced
diameter within the outer polymeric tubular layer 26 and the outer
polymeric covering 50. Once the self-expandable sheath is at least
partially inserted into a patient's vessel, the outer polymeric
covering 50 can be slid back, peeled away, or otherwise at least
partially removed from the sheath. To facilitate removal of the
outer polymeric covering 50, a portion of the outer polymeric
covering 50 can remain outside the patient's vessel, and that
portion can be pulled back or removed from the sheath to allow the
sheath to expand. In some embodiments, substantially the entire
outer polymeric covering 50 can be inserted, along with the sheath,
into a patient's vessel. In these embodiments, an external
mechanism attached to the outer polymeric covering 50 can be
provided, such that the outer polymeric covering can be at least
partially removed from the sheath once the sheath is inserted into
a patient's vessel.
Once no longer constrained by the outer polymeric covering 50, the
radially compressed intermediate layer 28 can self-expand, causing
expansion of the sheath along the length of the intermediate layer
28. In some embodiments, portions of the sheath can radially
collapse, at least partially returning to the original crimped
state, as the sheath is being withdrawn from the vessel after
completion of the surgical procedure. In some embodiments, such
collapse can be facilitated and/or encouraged by an additional
device or layer that, in some embodiments, can be mounted onto a
portion of the sheath prior to the sheath's insertion into the
vessel.
The outer polymeric covering 50, in some embodiments, is not
adhered to the other layers of the sheath 22. For example, the
outer polymeric covering 50 may be slidable with respect to the
underlying sheath, such that it can be easily removed or retracted
from its initial position on the sheath 22.
As seen in FIG. 8, the outer polymeric covering 50 can include one
or more peel tabs 54 to facilitate manual removal of the outer
polymeric covering 50. The outer polymeric covering 50 can be
automatically or manually retractable and/or splittable to
facilitate radial expansion of the sheath 22. Peel tabs 54 can be
located approximately 90 degrees from any cut or notch present in
the outer polymeric covering 50, and approximately 180 degrees
offset from one another. In alternative embodiments, the peel tabs
54 can extend substantially around the circumference of the outer
polymeric covering 50, thus resulting in a single circular peel tab
54.
Suitable materials for the outer polymeric covering 50 are similar
to those materials suitable for the inner polymeric tubular layer
and the outer polymeric tubular layer, and can include PTFE and/or
high density polyethylene.
Turning now to the intermediate tubular layer 28, several different
configurations are possible. The intermediate tubular layer 28 is
generally a thin, hollow, substantially cylindrical tube comprising
an arrangement, pattern, structure, or configuration of wires or
struts, however other geometries can also be used. The intermediate
tubular layer 28 can extend along substantially the entire length
of the sheath 22, or alternatively, can extend only along a portion
of the length of sheath 22. Suitable wires can be round, ranging
from about 0.0005 inches thick to about 0.10 inches thick, or flat,
ranging from about 0.0005 inches.times.0.003 inches to about 0.003
inches.times.0.007 inches. However, other geometries and sizes are
also suitable for certain embodiments. If braided wire is used, the
braid density can be varied. Some embodiments have a braid density
of from about thirty picks per inch to about eighty picks per inch
and can include up to thirty-two wires in various braid
patterns.
One representative embodiment of an intermediate tubular layer
comprises a braided Nitinol composite which is at least partially
encapsulated by an inner polymeric tubular member and an outer
polymeric tubular member disposed on inner and outer surfaces of
the intermediate tubular layer, respectively. Such encapsulation by
polymeric layers can be accomplished by, for example, fusing the
polymeric layers to the intermediate tubular layer, or dip coating
the intermediate tubular layer. In some embodiments, an inner
polymeric tubular member, an intermediate tubular layer, and an
outer polymeric tubular layer can be arranged on a mandrel, and the
layers can then be thermally fused or melted into one another by
placing the assembly in an oven or otherwise heating it. The
mandrel can then be removed from the resulting sheath. In other
embodiments, dip coating can be used to apply an inner polymeric
tubular member to the surface of a mandrel. The intermediate
tubular layer can then be applied, and the inner polymeric tubular
member allowed to cure. The assembly can then be dip coated again,
such as to apply a thin coating of, for example, polyurethane,
which will become the outer polymeric tubular member of the sheath.
The sheath can then be removed from the mandrel.
Additionally, the intermediate tubular layer 28 can be, for
example, braided or laser cut to form a pattern or structure, such
that the intermediate tubular layer 28 is amenable to radial
expansion. FIGS. 9-23 illustrate partial elevation views of various
structures for the intermediate tubular layer. Some illustrated
structures, such as those shown in FIGS. 11-14 and 23, include at
least one discontinuity. For example, the struts 56, 58, 60, 62, 64
shown in FIGS. 11, 12, 13, 14, and 23, respectively, result in a
discontinuous intermediate tubular layer 28 in that the struts 56,
58, 60, 62, 64 separate adjacent sections of the intermediate
tubular layer 28 from each other, where the sections are spaced
apart from each other along a longitudinal axis parallel to the
lumen of the sheath. Thus, the structure of the intermediate
tubular layer 28 can vary from section to section, changing along
the length of the sheath.
The structures shown in FIGS. 9-23 are not necessarily drawn to
scale. Components and elements of the structures can be used alone
or in combination within a single intermediate tubular layer 28.
The scope of the intermediate tubular layer 28 is not meant to be
limited to these particular structures; they are merely exemplary
embodiments.
Alternative embodiments of a sheath for introducing a prosthetic
device are also described. For example, FIGS. 24-26 illustrate a
section view and a perspective view, respectively, of a sheath 66
for introducing a prosthetic device into a body. The sheath 66
comprises an inner layer, such as inner polymeric layer 68, an
outer layer, such as polymeric tubular layer 70, and a hemostasis
valve (not shown). The inner polymeric layer 68 and the outer
polymeric tubular layer 70 at least partially enclose a lumen 72,
through which a delivery apparatus and prosthetic device can pass
from outside the patient's body into the patient's vessel. Either
or both of the inner polymeric layer 68 and the outer polymeric
layer 70 can be provided with at least one longitudinal notch
and/or cut to facilitate radial expansion of the sheath.
For example, FIG. 24 illustrates a longitudinal notch 74 in the
inner polymeric layer 68 that can facilitate radial expansion of
the sheath 66. The longitudinal notch 74 can separate or split open
completely upon application of a radial force due to insertion of a
delivery apparatus or prosthetic device. Similarly, FIG. 25
illustrates a longitudinal cut 76 in the inner polymeric layer 68
that can also facilitate radial expansion of the sheath 66. The
outer polymeric layer 70 can, additionally or alternatively,
comprise one or more longitudinal cuts 76 or notches 74. Such cuts
and/or notches, whether in the inner polymeric layer 68 or the
outer polymeric layer 70, can extend substantially through the
entire thickness of the layer, or can extend only partially through
the thickness of the layer. The cuts and/or notches can be
positioned at or near the inner or outer surface, or both surfaces,
of the inner and/or outer polymeric layers 68, 70.
FIG. 26 illustrates a perspective view of one embodiment of an
inner polymeric layer 68 with longitudinal notches 74 and a
longitudinal cut 76. More or fewer notches 74 and/or cuts 76 can be
provided. For clarity, the outer polymeric layer 70 is not shown in
FIG. 26. As shown in FIG. 26, longitudinal notches 74 and/or cuts
76 can extend only along a portion of the length of sheath 66. In
alternative embodiments, one or more notches 74 and/or cuts 76 can
extend substantially along the entire length of the sheath 66.
Additionally, notches 74 and/or cuts 76 can be positioned randomly
or patterned.
One particular embodiment of a sheath 66 comprises a sheath having
a notch or cut in the outer polymeric layer 70 or the inner
polymeric layer 68 that extends longitudinally along approximately
75% of the length of the sheath 66. If such a notch or cut extends
only partially through the associated layer, it can have a
relatively low tear force, such as a tear force of about 0.5 lbs.,
so that the notch splits open relatively easily during use.
The inner polymeric layer 68 and the outer polymeric layer 70 can
optionally be adhered together or otherwise physically associated
with one another. The amount of adhesion between the inner
polymeric layer 68 and the outer polymeric layer 70 can be variable
over the surfaces of the layers. For example, little to no adhesion
can be present at areas around or near any notches and/or cuts
present in the layers, so as not to hinder radial expansion of the
sheath 66. Adhesion between the layers can be created by, for
example, thermal bonding and/or coatings. Embodiments of a sheath
66 can be formed from an extruded tube, which can serve as the
inner polymeric layer 68. The inner polymeric layer 68 can be
surface treated, such as by plasma etching, chemical etching or
other suitable methods of surface treatment. By treating the
surface of the inner polymeric layer 68, the outer surface of the
inner polymeric layer 68 can have areas with altered surface angles
that can provide better adhesion between the inner polymeric layer
68 and the outer polymeric layer 70. The treated inner polymeric
layer can be dip coated in, for example, a polyurethane solution to
form the outer polymeric layer 70. In some configurations, the
polyurethane may not adhere well to untreated surface areas of the
inner polymeric layer 68. Thus, by surface treating only surface
areas of the inner polymeric layer 68 that are spaced away from the
areas of expansion (e.g. the portion of the inner polymeric layer
68 near notches 74 and/or cuts 76), the outer polymeric layer 70
can be adhered to some areas of the inner polymeric layer 68, while
other areas of the inner polymeric layer 68 remain free to slide
relative to the outer polymeric layer 70, thus allowing for
expansion of the diameter of the sheath 66. Thus, areas around or
near any notches 74 and/or cuts 76 can experience little to no
adhesion between the layers, while other areas of the inner and
outer polymeric layers 68, 70 can be adhesively secured or
otherwise physically associated with each other.
As with previously disclosed embodiments, the embodiments
illustrated in FIGS. 24-26 can be applied to sheaths having a wide
variety of inner and outer diameters. Applications can utilize a
sheath of the present disclosure with an inner diameter of the
inner polymeric layer 68 that is expandable to an expanded diameter
of from about 3 Fr to about 26 Fr. The expanded diameter can vary
slightly along the length of the sheath 66. For example, the
expanded outer diameter at the proximal end of the sheath 66 can
range from about 3 Fr to about 28 Fr, while the expanded outer
diameter at the distal end of the sheath 66 can range from about 3
Fr to about 25 Fr. Embodiments of a sheath 66 can expand to an
expanded outer diameter that is from about 10% greater than the
original unexpanded outer diameter to about 100% greater than the
original unexpanded outer diameter.
In some embodiments, the outer diameter of the sheath 66 gradually
decreases from the proximal end of the sheath 66 to the distal end
of the sheath 66. For example, in one embodiment, the outer
diameter can gradually decrease from about 26 Fr at the proximal
end to about 18 Fr at the distal end. The diameter of the sheath 66
can transition gradually across substantially the entire length of
the sheath 66. In other embodiments, the transition or reduction of
the diameter of the sheath 66 can occur only along a portion of the
length of the sheath 66. For example, the transition can occur
along a length from the proximal end to the distal end, where the
length can range from about 0.5 inches to about the entire length
of sheath 66.
Suitable materials for the inner polymeric layer 68 can have a high
elastic strength and include materials discussed in connection with
other embodiments, especially Teflon (PTFE), polyethylene (e.g.
high density polyethylene), fluoropolymers, or combinations
thereof. In some embodiments, the inner polymeric layer 68
preferably has a low coefficient of friction, such as a coefficient
of friction of from about 0.01 to about 0.5. Some preferred
embodiments of a sheath 66 comprise an inner polymeric layer 68
having a coefficient of friction of about 0.1 or less.
Likewise, suitable materials for the outer polymeric layer 70
include materials discussed in connection with other embodiments,
and other thermoplastic elastomers and/or highly elastic
materials.
The Shore hardness of the outer polymeric layer 70 can be varied
for different applications and embodiments. Some embodiments
include an outer polymeric layer with a Shore hardness of from
about 25 A to about 80 A, or from about 20 D to about 40 D. One
particular embodiment comprises a readily available polyurethane
with a Shore hardness of 72 A. Another particular embodiment
comprises a polyethylene inner polymeric layer dipped in
polyurethane or silicone to create the outer polymeric layer.
The sheath 66 can also include a radiopaque filler or marker as
described above. In some embodiments, a distinct radiopaque marker
or band can be applied to some portion of the sheath 66. For
example, a radiopaque marker can be coupled to the inner polymeric
layer 68, the outer polymeric layer 70, and/or can be positioned in
between the inner and outer polymeric layers 68, 70.
FIGS. 27A-27E and 28 illustrate section views of various
embodiments of unexpanded (FIGS. 27A-27E) and expanded (FIG. 28)
sheaths 66 according to the present disclosure. The sheath 66
includes a split outer polymeric tubular layer 70 having a
longitudinal cut 76 through the thickness of the outer polymeric
tubular layer 70 such that the outer polymeric tubular layer 70
comprises a first portion 78 and a second portion 80 separable from
one another along the cut 76. An expandable inner polymeric layer
68 is associated with an inner surface 82 of the outer polymeric
tubular layer 70, and, in the unexpanded configuration shown in
FIG. 27A, a portion of the inner polymeric layer 68 extends through
a gap created by the cut 76 and can be compressed between the first
and second portions 78, 80 of the outer polymeric tubular layer 70.
Upon expansion of the sheath 66, as shown in FIG. 28, first and
second portions 78, 80 of the outer polymeric tubular layer 70 have
separated from one another, and the inner polymeric layer 68 is
expanded to a substantially cylindrical tube. In some embodiments,
two or more longitudinal cuts 76 may be provided through the
thickness of the outer polymeric tubular layer 70. In such
embodiments, a portion of the inner polymeric layer 68 may extend
through each of the longitudinal cuts 76 provided in the outer
polymeric tubular layer 70.
Preferably, the inner polymeric layer 68 comprises one or more
materials that are elastic and amenable to folding and/or pleating.
For example, FIG. 27A illustrates an inner polymeric layer 68 with
folded regions 85. As seen in FIGS. 27A-27E, the sheath 66 can be
provided with one or more folded regions 85. Such folded regions 85
can be provided along a radial direction and substantially conform
to the circumference of the outer polymeric tubular layer 70. At
least a portion of the folded regions 85 can be positioned adjacent
the outer surface 83 of the outer polymeric tubular layer 70.
Additionally, as shown in FIGS. 27B and 27E, at least a portion of
the folded region or regions 85 can be overlapped by an outer
covering, such as outer polymeric covering 81. The outer polymeric
covering 81 can be adjacent at least a portion of the outer surface
83 of the outer polymeric tubular layer 70. The outer polymeric
covering 81 serves to at least partially contain the folded regions
85 of the inner polymeric layer 68, and can also prevent the folded
regions 85 from separating from the outer polymeric tubular layer
70 when, for example, the sheath 66 undergoes bending. In some
embodiments, the outer polymeric covering 81 can be at least
partially adhered to the outer surface 83 of the outer polymeric
tubular layer 70. The outer polymeric covering 81 can also increase
the stiffness and/or durability of the sheath 66. Additionally, as
shown in FIGS. 27B and 27E, the outer polymeric covering 81 may not
entirely overlap the circumference of the sheath 66. For example,
the outer polymeric covering 81 may be provided with first and
second ends, where the ends do not contact one another. In these
embodiments, only a portion of the folded region 85 of the inner
polymeric layer 68 is overlapped by the outer polymeric covering
81.
In embodiments having a plurality of folded regions 85, the regions
can be equally displaced from each other around the circumference
of the outer polymeric tubular layer 70. Alternatively, the folded
regions can be off-center, different sizes, and/or randomly spaced
apart from each other. While portions of the inner polymeric layer
68 and the outer tubular layer 70 can be adhered or otherwise
coupled to one another, the folded regions 85 preferably are not
adhered or coupled to the outer tubular layer 70. For example,
adhesion between the inner polymeric layer 68 and the outer tubular
layer 70 can be highest in areas of minimal expansion.
One particular embodiment of the sheath illustrated in FIGS. 27A-28
comprises a polyethylene (e.g. high density polyethylene) outer
polymeric tubular layer 70 and a PTFE inner polymeric layer 68.
However, other materials are suitable for each layer, as described
above. Generally, suitable materials for use with the outer
polymeric tubular layer 70 include materials having a high
stiffness or modulus of strength that can support expansion and
contraction of the inner polymeric layer 68.
In some embodiments, the outer polymeric tubular layer 70 comprises
the same material or combination of materials along the entire
length of the outer polymeric tubular layer 70. In alternative
embodiments, the material composition can change along the length
of the outer polymeric tubular layer 70. For example, the outer
polymeric tubular layer can be provided with one or more segments,
where the composition changes from segment to segment. In one
particular embodiment, the Durometer rating of the composition
changes along the length of the outer polymeric tubular layer 70
such that segments near the proximal end comprise a stiffer
material or combination of materials, while segments near the
distal end comprise a softer material or combination of materials.
This can allow for a sheath 66 having a relatively stiff proximal
end at the point of introducing a delivery apparatus, while still
having a relatively soft distal tip at the point of entry into the
patient's vessel.
As with other disclosed embodiments, the embodiments of sheath 66
shown in FIGS. 27A-28 can be provided in a wide range of sizes and
dimensions. For example, the sheath 66 can be provided with an
unexpanded inner diameter of from about 3 Fr to about 26 Fr. In
some embodiments, the sheath 66 has an unexpanded inner diameter of
from about 15 Fr to about 16 Fr. In some embodiments, the
unexpanded inner diameter of the sheath 66 can range from about 3
Fr to about 26 Fr at or near the distal end of sheath 66, while the
unexpanded inner diameter of the sheath 66 can range from about 3
Fr to about 28 Fr at or near the proximal end of sheath 66. For
example, in one unexpanded embodiment, the sheath 66 can transition
from an unexpanded inner diameter of about 16 Fr at or near the
distal end of the sheath 66 to an unexpanded inner diameter of
about 26 Fr at or near the proximal end of the sheath 66.
The sheath 66 can be provided with an unexpanded outer diameter of
from about 3 Fr to about 30 Fr, and, in some embodiments has an
unexpanded outer diameter of from about 18 Fr to about 19 Fr. In
some embodiments, the unexpanded outer diameter of the sheath 66
can range from about 3 Fr to about 28 Fr at or near the distal end
of sheath 66, while the unexpanded outer diameter of the sheath 66
can range from about 3 Fr to about 30 Fr at or near the proximal
end of sheath 66. For example, in one unexpanded embodiment, the
sheath 66 can transition from an unexpanded outer diameter of about
18 Fr at or near the distal end of the sheath 66 to an unexpanded
outer diameter of about 28 Fr at or near the proximal end of the
sheath 66.
The thickness of the inner polymeric layer 68 can vary, but in some
preferred embodiments is from about 0.002 inches to about 0.015
inches. In some embodiments, expansion of the sheath 66 can result
in expansion of the unexpanded outer diameter of from about 10% or
less to about 430% or more.
As with other illustrated and described embodiments, the
embodiments shown in FIGS. 27A-28 can be provided with a radiopaque
filler and/or a radiopaque tip marker as described above. The
sheath 66 can be provided with a radiopaque tip marker provided at
or near the distal tip of the sheath 66. Such a radiopaque tip
marker can comprise materials such as those suitable for the
radiopaque filler, platinum, iridium, platinum/iridium alloys,
stainless steel, other biocompatible metals, or combinations
thereof.
FIGS. 29A-29D show section views of other possible configurations
of a sheath 66 for introducing a prosthetic device into a patient's
vasculature. The sheath 66 comprises a polymeric tubular layer 84
having an inner surface 86 and an outer surface 88. The thickness
of the polymeric tubular layer 84 extends from the inner surface 86
to the outer surface 88. As shown in FIGS. 29B-29D, the polymeric
tubular layer 84 can be formed with at least a first angular
portion 90 of reduced thickness adjacent the inner surface 86 and a
second angular portion 92 of reduced thickness adjacent the outer
surface 88, with the second portion 92 at least partially
overlapping the first portion 90. FIG. 29A illustrates a similar
configuration, where a second portion 92 at least partially
overlaps a first portion 90 in a partial coil configuration. In the
embodiment of FIG. 29A, the second portion 92 and the first portion
90 can have the same thickness.
In preferred embodiments, the first and second portions 90, 92 are
not adhered to one another. In some embodiments, and best seen in
FIG. 29A, there can be a small gap 94 between the first and second
portions 90, 92 that can give the sheath 66 the appearance of
having two interior lumens 72, 94. FIGS. 29A-29D illustrate the
sheath 66 in unexpanded configurations. Preferably, upon expansion
of the sheath 66, the ends of the first and second portions 90, 92
abut or are in close proximity to each other to reduce or eliminate
any gap between them.
In some embodiments, a sheath 66 can comprise a partial slit or
score line along at least a portion of its length. For example, as
shown in FIG. 33, a sheath 66 can comprise an outer polymeric
tubular layer 70 over an inner polymeric layer 68. The inner
polymeric layer can extend through a cut in the outer polymeric
tubular layer 70, to form a folded region 85 on the outer surface
of the outer polymeric tubular layer 70, such as also shown in FIG.
27C. The folded region 85 of the inner layer, in some embodiments,
terminates before the outer polymeric tubular layer 70 (i.e. the
outer polymeric tubular layer 70 is longer than the inner layer).
As shown in FIG. 33, in these embodiments, the sheath 66 can
comprise a partial slit or score line 77 that can extend from the
termination (distal end) 75 of the folded region 85 to the distal
end 40 of the sheath 66. In some embodiments, score line 77 can
facilitate expansion of the sheath 66.
Score line 77 can be substantially centrally located with respect
to the folded region 85. In alternative embodiments, score line 77
can be positioned in other locations relative to the folded region
85. Also, sheath 66 can comprise one or more score lines 77. For
example, as shown in FIG. 34, one or more score lines 77 can be
peripherally located with respect to the folded region 85. The one
or more score lines 77 can be positioned anywhere around the
circumference of the outer polymeric tubular layer 70. In
embodiments comprising a radiopaque marker 69 as seen in FIG. 33, a
score line 77 can extend from, for example, the distal end of the
radiopaque marker 69 substantially to the distal end 40 of the
sheath 66.
FIGS. 35 and 36 illustrate an expandable sheath 100 according to
the present disclosure, which can be used with a delivery apparatus
for delivering a prosthetic device, such as a tissue heart valve
into a patient. In general, the delivery apparatus can include a
steerable guide catheter (also referred to as a flex catheter), a
balloon catheter extending through the guide catheter, and a nose
catheter extending through the balloon catheter (e.g., as depicted
in FIG. 1). The guide catheter, the balloon catheter, and the nose
catheter can be adapted to slide longitudinally relative to each
other to facilitate delivery and positioning of the valve at an
implantation site in a patient's body. However, it should be noted
that the sheath 100 can be used with any type of elongated delivery
apparatus used for implanting balloon-expandable prosthetic valves,
self-expanding prosthetic valves, and other prosthetic devices.
Generally, sheath 100 can be inserted into a vessel (e.g., the
femoral or iliac arteries) by passing through the skin of patient,
such that a soft tip portion 102 at the distal end 104 of the
sheath 100 is inserted into the vessel. The sheath 100 can also
include a proximal flared end portion 114 to facilitate mating with
an introducer housing 101 and catheters mentioned above (e.g., the
proximal flared end portion 114 can provide a compression fit over
the housing tip and/or the proximal flared end portion 114 can be
secured to the housing 101 via a nut or other fastening device or
by bonding the proximal end of the sheath to the housing). The
introducer housing 101 can house one or more valves that form a
seal around the outer surface of the delivery apparatus once
inserted through the housing, as known in the art. The delivery
apparatus can be inserted into and through the sheath 100, allowing
the prosthetic device to be advanced through the patient's
vasculature and implanted within the patient.
Sheath 100 can include a plurality of layers. For example, sheath
100 can include an inner layer 108 and an outer layer 110 disposed
around the inner layer 108. The inner layer 108 can define a lumen
through which a delivery apparatus can travel into a patient's
vessel in order to deliver, remove, repair, and/or replace a
prosthetic device, moving in a direction along the longitudinal
axis X. As the prosthetic device passes through the sheath 100, the
sheath locally expands from a first, resting diameter to a second,
expanded diameter to accommodate the prosthetic device. After the
prosthetic device passes through a particular location of the
sheath 100, each successive expanded portion or segment of the
sheath 100 at least partially returns to the smaller, resting
diameter. In this manner, the sheath 100 can be considered
self-expanding, in that it does not require use of a balloon,
dilator, and/or obturator to expand.
The inner and outer layers 108, 110 can comprise any suitable
materials. Suitable materials for the inner layer 108 include
polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene
(ETFE), nylon, polyethylene, polyether block amide (e.g., Pebax),
and/or combinations thereof. In one specific embodiment the inner
layer 108 can comprise a lubricious, low-friction, or hydrophilic
material, such as PTFE. Such low coefficient of friction materials
can facilitate passage of the prosthetic device through the lumen
defined by the inner layer 108. In some embodiments, the inner
layer 108 can have a coefficient of friction of less than about
0.1. Some embodiments of a sheath 100 can include a lubricious
liner on the inner surface of the inner layer 108. Examples of
suitable lubricious liners include materials that can further
reduce the coefficient of friction of the inner layer 108, such as
PTFE, polyethylene, polyvinylidine fluoride, and combinations
thereof. Suitable materials for a lubricious liner also include
other materials desirably having a coefficient of friction of about
0.1 or less.
Suitable materials for the outer layer 110 include nylon,
polyethylene, Pebax, HDPE, polyurethanes (e.g., Tecoflex), and
other medical grade materials. In one embodiment, the outer layer
110 can comprise high density polyethylene (HDPE) and Tecoflex (or
other polyurethane material) extruded as a composite. In some
embodiments, the Tecoflex can act as an adhesive between the inner
layer 108 and the outer layer 110 and may only be present along a
portion of the inner surface of the outer layer 110. Other suitable
materials for the inner and outer layers are also disclosed in U.S.
Patent Application Publication No. 2010/0094392, which is
incorporated herein by reference.
Additionally, some embodiments of a sheath 100 can include an
exterior hydrophilic coating on the outer surface of the outer
layer 110. Such a hydrophilic coating can facilitate insertion of
the sheath 100 into a patient's vessel. Examples of suitable
hydrophilic coatings include the Harmony.TM. Advanced Lubricity
Coatings and other Advanced Hydrophilic Coatings available from
SurModics, Inc., Eden Prairie, Minn. DSM medical coatings
(available from Koninklijke DSM N.V, Heerlen, the Netherlands), as
well as other hydrophilic coatings (e.g., PTFE, polyethylene,
polyvinylidine fluoride), are also suitable for use with the sheath
100.
Best seen in FIG. 36, the soft tip portion 102 can comprise, in
some embodiments, low density polyethylene (LDPE) and can be
configured to minimize trauma or damage to the patient's vessels as
the sheath is navigated through the vasculature. For example, in
some embodiments, the soft tip portion 102 can be slightly tapered
to facilitate passage through the vessels. The soft tip portion 102
can be secured to the distal end 104 of the sheath 100, such as by
thermally bonding the soft tip portion 102 to the inner and outer
layers of the sheath 100. Such a soft tip portion 102 can be
provided with a lower hardness than the other portions of the
sheath 100. In some embodiments, the soft tip 102 can have a Shore
hardness from about 25 D to about 40 D. The tip portion 102 is
configured to be radially expandable to allow a prosthetic device
to pass through the distal opening of the sheath 100. For example,
the tip portion 102 can be formed with a weakened portion, such as
an axially extending score line or perforated line that is
configured to split and allow the tip portion to expand radially
when the prosthetic device passes through the tip portion (such as
shown in the embodiments of FIGS. 33 and 34).
FIG. 37 shows a cross-section view of the sheath 100 taken near the
distal end 104 of the sheath 100. As shown in FIGS. 36 and 37, the
sheath 100 can include at least one radiopaque filler or marker,
such as a discontinuous, or C-shaped, band 112 positioned near the
distal end 104 of the sheath 100. The marker 112 can be associated
with the inner and/or outer layers 108, 110 of the sheath 100. For
example, as shown in FIG. 37, the marker 112 can be positioned
between the inner layer 108 and the outer layer 110. In alternative
embodiments, the marker 112 can be associated with the outer
surface of the outer layer 110. In some embodiments, the marker 112
can be embedded or blended within the inner or outer layers 108,
110.
The C-shaped band 112 can serve as a radiopaque marker or filler,
to enable visibility of the sheath 100 under fluoroscopy during use
within a patient. The C-shaped band 112 can comprise any suitable
radiopaque material, such as barium sulfite, bismuth trioxide,
titanium dioxide, bismuth subcarbonate, platinum, iridium, and
combinations thereof. In one specific embodiment, the C-shaped band
can comprise 90% platinum and 10% iridium. In other embodiments,
the marker 112 need not be a C-shaped band. Other shapes, designs,
and configurations are possible. For example, in some embodiments,
the marker 112 can extend around the entire circumference of the
sheath 100. In other embodiments, the marker 112 can comprise a
plurality of small markers spaced around the sheath 100.
FIGS. 38 and 39 show additional cross sections taken at different
points along the sheath 100. FIG. 38 shows a cross-section of a
segment of the sheath near the proximal end 106 of the sheath 100,
as indicated by line 38-38 in FIG. 35. The sheath 100 at this
location can include inner layer 108 and outer layer 110. At this
location, near the proximal end of the sheath, the layers 108, 110
can be substantially tubular, without any slits or folded portions
in the layers. By contrast, the layers 108, 110 at different
locations along the sheath 100 (e.g., at the point indicated by
line 39-39 in FIG. 35) can have a different configuration.
As shown in FIG. 39, the inner layer 108 can be arranged to form a
substantially cylindrical lumen 116 therethrough. Inner layer 108
can include one or more folded portions 118. In the embodiment
shown in FIG. 39, inner layer 108 is arranged to have one folded
portion 118 that can be positioned on either side of the inner
layer 108. Inner layer 108 can be continuous, in that there are no
breaks, slits, or perforations in inner layer 108. Outer layer 110
can be arranged in an overlapping fashion such that an overlapping
portion 120 overlaps at least a part of the folded portion 118 of
the inner layer 108. As shown in FIG. 39, the overlapping portion
120 also overlaps an underlying portion 122 of the outer layer 110.
The underlying portion 122 can be positioned to underlie both the
overlapping portion 120 of the outer layer 110, as well as the
folded portion 118 of the inner layer 108. Thus, the outer layer
110 can be discontinuous, in that it includes a slit or a cut in
order to form the overlapping and underlying portions 120, 122. In
other words, a first edge 124 of the outer layer 110 is spaced
apart from a second edge 126 of the outer layer 110 so as not to
form a continuous layer.
As shown in FIG. 39, the sheath 100 can also include a thin layer
of bonding or adhesive material 128 positioned between the inner
and outer layers 108, 110. In one embodiment, the adhesive material
128 can comprise a polyurethane material such as Tecoflex. The
adhesive material 128 can be positioned on an inner surface 130 of
at least a portion of the outer layer 110 so as to provide adhesion
between selected portions of the inner and outer layers 108, 110.
For example, the outer layer 110 may only include a Tecoflex layer
128 around the portion of the inner surface 130 that faces the
lumen-forming portion of the inner layer 108. In other words, the
Tecoflex layer 128 can be positioned so that it does not contact
the folded portion 118 of the inner layer 108 in some embodiments.
In other embodiments, the Tecoflex layer 128 can be positioned in
different configurations as desired for the particular application.
For example, as shown in FIG. 39, the Tecoflex layer 128 can be
positioned along the entire inner surface 130 of the outer layer
110. In an alternative embodiment, the Tecoflex layer can be
applied to the outer surface of the inner liner 108 instead of the
inner surface of the outer layer. The Tecoflex layer can be applied
to all or selected portions on the inner layer; for example, the
Tecoflex layer can be formed only on the portion of the inner layer
that faces the lumen-forming portion of the outer layer and not on
the folded portion. The configuration of FIG. 39 allows for radial
expansion of the sheath 100 as an outwardly directed radial force
is applied from within (e.g., by passing a medical device such as a
prosthetic heart valve through the lumen 116). As radial force is
applied, the folded portion 118 can at least partially separate,
straighten, and/or unfold, and/or the overlapping portion 120 and
the underlying portion 122 of the outer layer 110 can slide
circumferentially with respect to one another, thereby allowing the
diameter of lumen 116 to enlarge.
In this manner, the sheath 100 is configured to expand from a
resting configuration (FIG. 39) to an expanded configuration shown
in FIG. 40. In the expanded configuration, as shown in FIG. 40, an
annular gap 132 can form between the longitudinal edges of the
overlapping portion 120 and the underlying portion 122 of the outer
layer 110. As the sheath 100 expands at a particular location, the
overlapping portion 120 of the outer layer 110 can move
circumferentially with respect to the underlying portion 122 as the
folded portion 118 of the inner layer 108 unfolds. This movement
can be facilitated by the use of a low-friction material for inner
layer 108, such as PTFE. Further, the folded portion 118 can at
least partially separate and/or unfold to accommodate a medical
device having a diameter larger than that of lumen 116 in the
resting configuration. As shown in FIG. 40, in some embodiments,
the folded portion of the inner layer 108 can completely unfold, so
that the inner layer 108 forms a cylindrical tube at the location
of the expanded configuration.
The sheath 100 can be configured such that it locally expands at a
particular location corresponding to the location of the medical
device along the length of the lumen 116, and then locally
contracts once the medical device has passed that particular
location. Thus, a bulge may be visible, traveling longitudinally
along the length of the sheath as a medical device is introduced
through the sheath, representing continuous local expansion and
contraction as the device travels the length of the sheath 100. In
some embodiments, each segment of the sheath 100 can locally
contract after removal of any radial outward force such that it
regains the original resting diameter of lumen 116. In some
embodiments, each segment of the sheath 100 can locally contract
after removal of any radial outward force such that it at least
partially returns to the original resting diameter of lumen
116.
The layers 108, 110 of sheath 100 can be configured as shown in
FIG. 39 along at least a portion of the length of the sheath 100.
In some embodiments, the layers 108, 110 can be configured as shown
in FIG. 39 along the length A (FIG. 35) extending from a location
adjacent the soft tip portion 102 to a location closer to the
proximal end 106 of the sheath 100. In this matter, the sheath is
expandable and contractable only along a portion of the length of
the sheath corresponding to length A (which typically corresponds
to the section of the sheath inserted into the narrowest section of
the patient's vasculature).
FIGS. 41-49 illustrate additional embodiments and variations on the
general sheath 100 described above. It is to be understood that the
variations (e.g., materials and alternate configurations) described
above with reference to FIGS. 35-40 can also apply to the
embodiments shown in FIGS. 41-49. Furthermore, the variations
described below with reference to FIGS. 41-49 can also be applied
to the sheath described in FIGS. 35-40.
FIGS. 41-43 illustrate a sheath 700 that additionally includes a
strain relief cover, also referred to as an elastic outer cover, or
an elastic cover 702 positioned around at least a part of an inner
layer 704 and outer layer 706. As shown in FIG. 41, the elastic
cover 702 can extend for a length L along at least a portion of the
main body of the sheath 700. In some embodiments, the elastic cover
702 can extend from the proximal end 708 of the sheath 700 and
towards the distal end 709 of the sheath. In some embodiments, the
elastic cover 702 extends only part way down the length of the
sheath 700. In alternate embodiments, the elastic cover 702 can
extend to a point adjacent the distal end 709, or can extend all
the way to the distal end 709 of sheath 700. Furthermore, the
elastic outer cover 702 need not extend all the way to the proximal
end 708 of the sheath 700. In some embodiments, the elastic outer
cover 702 may extend only part way towards the proximal end 708. In
some embodiments, the longitudinal length L of the elastic cover
702 can range from about 10 cm to the entire length of the sheath
700.
As shown in FIGS. 42 and 43, the elastic cover 702 can be a
continuous tubular layer, without slits or other discontinuities.
The elastic cover 702 can be positioned to surround the entire
circumference of outer layer 706, and can extend longitudinally
along any portion of the length of the sheath 700. The elastic
outer cover 702 can comprise any pliable, elastic material(s) that
expand and contract, preferably with a high expansion ratio.
Preferably, the materials used can include low durometer polymers
with high elasticity, such as Pebax, polyurethane, silicone, and/or
polyisoprene. Materials for the elastic outer cover 702 can be
selected such that it does not impede expansion of the sheath 700.
In fact, the elastic outer cover 702 can stretch and expand as the
sheath 700 expands, such as by movement of the folded or scored
inner liner with respect to itself.
The elastic outer cover 702 can, in some embodiments, provide
hemostasis (e.g., prevent blood loss during implantation of the
prosthetic device). For example, the elastic outer cover 702 can be
sized or configured to form a seal with the patient's artery when
inserted, such that blood is substantially prevented from flowing
between the elastic outer cover 702 and the vessel wall. The
elastic outer cover 702 can be inserted such that it passes the
arteriotomy. For example, in embodiments where the elastic outer
cover 702 does not extend all the way to the distal end 709 of the
sheath 700, the elastic cover 702 can extend distally far enough
such that when the sheath 700 is fully inserted into the patient,
at least part of the elastic outer cover extends through the
ateriotomoy site.
The elastic outer cover can have a thickness ranging from, for
example, about 0.001'' to about 0.010.'' In some embodiments, the
outer cover can have a thickness of from about 0.003'' to about
0.006.'' The elastic outer over can be configured to expand as the
sheath expands, as shown in the expanded configuration in FIG.
43.
FIG. 42 shows a cross-section of the sheath 700 in a resting
configuration having an inner diameter D.sub.1. FIG. 43 shows a
cross-section of the sheath 700 in an expanded configuration,
having an inner diameter D.sub.2, where D.sub.2 is greater than
D.sub.1. Similar to the embodiment of FIGS. 35-40, the sheath 700
can include an inner layer 704 having a folded portion 710, and an
outer layer 706 having an overlapping portion 712 and an underlying
portion 714. The overlapping portion 712 overlaps at least a
portion of the folded portion 710 of the inner layer, and the
underlying portion 714 underlies at least a portion of the folded
portion 710. As shown in FIGS. 42-43, in some embodiments, the
overlapping portion 712 does not overlap the entire folded portion
710 of the inner layer 704, and thus a portion of the folded
portion 710 can be directly adjacent to the elastic outer cover 702
in locations where the elastic cover 702 is present. In locations
where the elastic cover 702 is not present, part of the folded
portion 710 may be visible from the outside of the sheath 700, as
seen in FIG. 41. In these embodiments, the sheath 700 can include a
longitudinal seam 722 where the overlapping portion 712 terminates
at the folded portion 710. In use, the sheath can be positioned
such that the seam 722 is posterior to the point of the sheath that
is 180 degrees from the seam 722 (e.g., facing downward in the view
of FIG. 41). The seam 722 can also be seen in FIG. 41, which shows
that the seam 722 need not extend the entire length of the sheath.
In some embodiments, the proximal end portion of the sheath
includes two layers without a folded portion (e.g., similar to FIG.
38) while the distal end portion of the sheath includes two layers
with a folded portion (e.g., similar to FIG. 39). In some
embodiments, the seam 722 can end at a transition point between
portions of the sheath having a folded inner layer and portions of
the sheath not having a folded inner layer.
In some embodiments, the folded portion 710 can include a weakened
portion, such as a longitudinal perforation, score line, and/or
slit 716 along at least a portion of the length of the inner layer
704. The slit 716 can allow for two adjacent ends 718, 720 of the
folded portion 710 to move relative to one another as the sheath
700 expands to the expanded configuration shown in FIG. 43. As a
device having an outer diameter device larger than the initial
resting inner diameter of the sheath 700 is inserted through the
sheath 700, the device can cause local expansion of the sheath 700
and cause the sheath 700 to expand at the partial score or split
line location 716. The weakened portion 716 can extend
longitudinally along any portion of the expandable sheath 700.
FIGS. 44 and 45 show another embodiment of an expandable sheath 800
having an initial diameter in a resting configuration (FIG. 44) and
a larger expanded diameter in an expanded configuration (FIG. 45).
The sheath 800 can include an elastic outer cover 802, an inner
layer 804, and an outer layer 806. Inner layer 804 can include
first and second folded portions 808, 810. The folded portions 808,
810 can be arranged such that they fold away from one another in
opposite directions around the circumference of the sheath 800. For
example, folded portion 808 can be folded to the right in the view
of FIG. 44 and folded portion 810 can be folded to the left such
that they do not overlap one another, but share a common segment
812 which is part of both folded portions 808, 810. In contrast to
previous embodiments, the outer layer 806 does not include an
overlapping portion in this embodiment, but rather has first and
second underlying portions 814, 816, which underlie the first and
second folded portions 808, 810, respectively. The inner layer 804
can extend through a gap between the ends of the adjacent
underlying portions 814, 816 (e.g., between a first end and a
second end of discontinuous outer layer 806).
Each folded portion 808, 810 can include a weakened portion 818,
such as a slit, score line, and/or perforation. Weakened portion
818 can allow the expandable sheath 800 to expand easily without a
high radial force. As the sheath 800 expands, segment 812 along the
top of the folded portions 808, 810 of inner layer 804 can be
configured to split apart from the rest of the folded portions 808,
810 and the first and second underlying portions 814, 816 can move
away from one another so as to create an enlarged lumen within the
inner layer 804. Weakened portions 818 can allow for the segment
812 to easily split apart from the inner layer 804 as the sheath
800 expands.
FIGS. 46-47 show another embodiment of an expandable sheath 900.
Sheath 900 can be provided with an inner layer 902 and an elastic
cover 904 surrounding the inner layer 902. While not shown, sheath
900 can additionally include an intermediate layer positioned
between the inner layer 902 and the elastic cover 904. If present,
the intermediate layer can closely follow the contour of the inner
layer 902.
Inner layer 902 can be shaped to include one or more folded
portions 906 arranged to form a generally horseshoe-shaped lumen
908 that extends longitudinally through sheath 900 along the inner
surface of the inner layer 902. The folded portions 906 can be
arranged to form an area 910 positioned with the lumen 908 and
radially inward from the elastic cover 904. In some embodiments,
the area 910 can include one or more voids (e.g., smaller lumens or
openings extending through portion 910). In some embodiments, the
area 910 can be filled with material (e.g., HDPE) reflowed from an
intermediate layer while the sheath is being made. In some
embodiments, the area 910 can be filled with material reflowed from
the elastic cover 904 during the sheath manufacturing process.
The inner layer 902 can include one or more weakened portions 912,
such as score lines, perforations, or slits. The weakened portions
912 can be configured to split apart, separate, or widen as the
sheath expands from its initial resting configuration (FIG. 46) to
an expanded configuration (FIG. 47) in the presence of a radial
force. As the sheath 900 expands, material from the area 910 can
cover any gaps 914 formed at the weakened portions 912, thereby
keeping the lumen 908 substantially sealed.
FIG. 48 shows another embodiment of an expandable sheath 1000
having an inner layer 1002 and a discontinuous outer layer 1004.
Sheath 1000 is similar to the sheath 800 of FIG. 44, except that
sheath 1000 is shown without an elastic outer cover and further,
the inner layer 1002 is continuous, without weakened portions at
the folds 1006. As shown in FIG. 48, the inner layer 1002 can be
configured to have one or more folds 1006 (e.g., two folds
positioned on the outer surface of the outer layer 1004), with
portions 1008 of the outer layer 1004 extending between the folds
1006 and the outer surface 1010 of the inner layer 1002 underlying
the folds 1006.
FIG. 49 shows yet another embodiment of an expandable sheath 1100
having an inner layer 1102 and an outer layer 1104. The sheath 1100
is similar to the sheath 100 shown in FIG. 39 in that the inner
layer 1102 can be continuous with a folded portion 1106, and the
outer layer 1104 can be discontinuous with an overlapping portion
1108 overlapping at least a part of the folded portion 1106 and an
underlying portion 1110 underlying at least a part of the folded
portion 1106. The underlying portion 1110 can thus be positioned
between an outer surface 1112 of the lumen-forming portion of the
inner layer 1102 and the folded portion 1106.
The inner layers 1002, 1102 of the sheaths 1000, 1100,
respectively, of FIGS. 48-49 can be optimized to perform slightly
differently than the inner layers of sheaths described above. For
example, different materials can be used for the inner liner to
increase durability and softness of the seam (although such
materials can also be used with the other embodiments of expandable
sheaths described above). For example, materials such as woven
fabrics or braid filaments can be used. Such fabrics, filaments, or
yarns can comprise, for example, PTFE, PET, PEEK, and/or nylon
yarns or filaments. These materials can advantageously provide a
soft and flexible layer that can be easily formed into the desired
shapes or folded portions. Additionally, such materials can
withstand high temperatures, as well as can possess high tensile
strength and tear resistance. Nonetheless, these materials can also
be elastic, experience minimal kinking, and provide soft distal
edges for less traumatic insertion into a patient's vessels.
Various methods can be used to produce the sheaths discussed above
and below, throughout the present disclosure. For example, a method
of making the sheath shown in FIGS. 2A-2D can comprise providing a
mandrel and applying an inner layer on the mandrel, such as by
spray coating or dip coating the mandrel. An intermediate layer,
such as a mesh structure, can then be mounted on the inner layer.
An outer layer can be applied over the intermediate layer, such as
by a second spray coating or dip coating step. Methods can comprise
etching or surface treating at least a portion of the inner layer.
Also, methods can comprise providing one or more notches and/or
cuts in the inner layer and/or the outer layer. Cuts and/or notches
can be provided by, for example, laser cutting or etching one or
more layers.
In some embodiments of methods of making a sheath such as the
sheaths illustrated in FIGS. 2A-2D, layers can be pre-formed and
mounted on a mandrel, and then fused or thermally bonded together.
For example, in one method, an inner layer is applied to a mandrel.
An intermediate layer can be applied to the outer surface of the
inner layer. An outer layer can be applied to the outer surface of
the intermediate layer. Heat shrink tubing can be applied, and the
assembly heated, such that the inner layer, the intermediate layer,
and/or the outer layer are thermally bonded and compressed together
under the heat shrink tubing.
FIG. 30 illustrates a block diagram of one method of producing a
sheath for use with a delivery apparatus in minimally invasive
surgery. One or more mandrels can be provided (step 300). The
mandrel can be provided with an exterior coating, such as a
Teflon.RTM. coating, and the mandrel's diameter can be
predetermined, based on the desired size of the resulting sheath. A
liner that will become the inner polymeric layer of the sheath,
such as a PTFE or high density polyethylene liner, can be mounted
on the mandrel (step 302). The liner can be etched and/or surface
treated prior to being mounted on the mandrel, according to
conventional etching and surface treatment methods. FIG. 32A
illustrates a section view of a sheath at steps 300 and 302 of FIG.
30. A coated mandrel 96 is inserted within the lumen 72 of the
inner polymeric layer 68. The circumference of the inner polymeric
layer 68 is larger than the circumference of the mandrel 96, such
that an excess portion of the inner polymeric layer 68 can be
gathered above the mandrel 96.
A layer of material that will become the outer polymeric tubular
layer, such as a layer comprising polyurethane or polyolefin, can
be cut or notched through all, substantially all, or a part of the
thickness of the layer (step 304). Such a cut or notch can extend
longitudinally along the length of the layer and can extend along
substantially the entire length of the outer polymeric tubular
layer. In alternative embodiments, the cut or notch can be provided
along only a portion of the outer polymeric tubular layer. For
example, the outer polymeric tubular layer can be cut starting at
the distal end of the outer polymeric tubular layer, with the cut
ending before the proximal end of the outer polymeric tubular
layer. In one embodiment, the cut can end at a transition, where
the outer diameter of the outer polymeric tubular layer increases
or decreases. In one specific embodiment, the cut or notch can
extend longitudinally along about 75% of the length of the
sheath.
The cut or notched outer polymeric tubular layer can be applied,
positioned, adhered, mounted, thermally fused or bonded, dip
coated, and/or otherwise coupled to the etched inner liner (step
306). FIG. 32B shows a section view of the sheath at step 306 of
FIG. 30, with outer polymeric tubular layer 70 applied to the inner
polymeric layer 68 such that a portion of the inner polymeric layer
68 extends between the cut formed between first and second portions
78, 80 of the outer polymeric tubular layer 70.
In alternative embodiments, the outer polymeric tubular layer can
be notched or cut after being mounted on the inner liner/mandrel
assembly. The outer polymeric tubular layer can optionally be
provided with a hydrophilic coating and/or provided with additional
layers, such as being dip coated with polyurethane. Some portion of
the inner liner can protrude through the cut in the outer polymeric
tubular layer after such outer polymeric tubular layer is mounted
onto the inner liner/mandrel arrangement. Using, for example, a
split tool, the protruding portion of the inner liner can be folded
down onto the outer surface of the outer polymeric tubular layer
(step 308). In some embodiments, the protruding portion of the
inner liner is folded down along the entire length of the resulting
sheath, while in other embodiments, the protruding portion of the
inner liner is only present along a portion of the length of the
sheath, or is only folded down along a portion of the length of the
resulting sheath. FIG. 32C shows a section view of the sheath at
step 308 of FIG. 30. A split tool 98 is used to fold the excess
portion of inner polymeric layer 68 over a portion of the outer
surface 83 of the outer polymeric tubular layer 70. FIG. 32D shows
a section view of the sheath after completion of step 308 of FIG.
30. Split tool 98 has been removed, and folding of the excess
portion of the inner polymeric layer 68 has been completed. FIG.
32E shows a section view of an outer covering, such as outer
polymeric covering 99, that can be applied such that it overlaps a
portion of the folded portion of inner polymeric layer 68. The
outer polymeric covering 99 contacts at least a portion of the
outer surface 83 of the outer polymeric tubular layer 70.
A soft, atraumatic tip can be provided at the distal end of the
resulting sheath (step 310). Additional outer layers can also be
applied, if desired. Then, a layer of heat shrink tubing, such as
fluorinated ethylene propylene (FEP) heat shrink tubing, can be
positioned over the entire assembly (step 312). An appropriate
amount of heat is applied, thus shrinking the heat shrink tubing
and compressing the layers of the sheath together, such that
components of the sheath can be thermally bonded or fused together
where desired. Once the components of the sheath have been bonded
together, the heat shrink tubing can be removed (step 314).
Finally, the proximal end of the sheath can be adhered or otherwise
attached to a housing of a catheter assembly, and the sheath can be
removed from the mandrel (step 316).
FIG. 31 illustrates a block diagram of an alternative embodiment of
a method of making a sheath. An inner liner, such as an etched PTFE
tubing can be applied to a tapered mandrel, such as a 16 Fr tapered
mandrel, and trimmed to an appropriate length (step 200). A second
mandrel, such as a 0.070 inches diameter mandrel, can be inserted
in the lumen of the inner liner such that the mandrels are arranged
side by side in the inner liner (step 202). FIG. 32F shows a
section view of a sheath at steps 200 and 202 of FIG. 31. An inner
liner or inner polymeric layer 68 is applied on a first, tapered,
mandrel 96. A second mandrel 97 is inserted into the lumen 72 of
the inner polymeric layer 68 created by the excess portion of the
inner polymeric layer 68, as described.
A notched or cut outer polymeric tubular layer, such as high
density polyethylene tubing that has been notched or cut
longitudinally, can be slid onto the tapered mandrel and a portion
of the inner liner, starting at the distal end of the tapered
mandrel (step 204). The second mandrel can then be removed (step
206). FIG. 32G illustrates a perspective view of the sheath at
steps 204 and 206 of FIG. 31. A polymeric outer tubular layer 70
having a longitudinal cut is applied over the tapered mandrel 96
and inner polymeric layer 68. The outer tubular layer conforms to
the portion of the inner polymeric layer around the tapered mandrel
96, and the portion of the inner polymeric layer 68 around the
second mandrel 97 extends through the longitudinal cut in the outer
polymeric tubular layer 70.
A split tool can be inserted into the portion of the lumen of the
inner liner that was previously occupied by the second mandrel
(step 208). The split tool can then be used to form folds and/or
pleats in the excess portion of the inner liner which now extends
through the longitudinal cut in the outer polymeric tubular layer
(step 210). A radiopaque marker band can optionally be applied at
the distal end of the sheath (step 212). Heat shrink tubing, such
as FEP heat shrink tubing, can be applied over the entire sheath,
and heat can be applied to compress the components of the sheath
and bond or fuse them together (step 214). The split tool, heat
shrink tubing, and second mandrel can then be removed (step 216).
The sheath can then be utilized with a delivery apparatus, such as
by bonding the proximal end of the sheath to a polycarbonate
housing of a delivery apparatus or catheter assembly (step
218).
FIG. 32H illustrates an elevation view of the sheath at step 218 of
FIG. 31. The sheath 66, made according to described methods and
processes, can be attached or bonded to a housing 101, such as by
bonding the proximal end of the sheath 66 to the polycarbonate
housing 101.
In another example, disclosed expandable sheaths can be made using
a reflowed mandrel process. A mandrel can be provided, with the
size of the mandrel defining the inner diameter of the sheath lumen
in its resting configuration. A tube of material, such as a PTFE
tube that will become the sheath's inner liner, can be provided
with an inner diameter greater than that of the mandrel (e.g., a 9
mm PTFE tube can be mounted on a 6 mm mandrel). The PTFE tube can
be mounted on the mandrel and prepared into the final folded
configuration by folding the excess material of the PTFE tube over
to one or both sides. An HDPE tube that will serve as the outer
layer can then be placed over the PTFE liner. The two layer
assembly can then be thermally fused together. For example, a
reflow process can be performed where the assembly is heated to a
temperature high enough such that the inner and/or outer layers are
at least partially melted and are then fused together as the heat
is removed and the assembly cools.
An elastic cover can be placed over at least part of the fused
layers (e.g., over a proximal section of the sheath) and held in
place using a thermal process. In some embodiments, the same
thermal process can bond the layers of the sheath and the elastic
cover. In other embodiments, a first thermal process can be used to
fuse the layers of the sheath, and a second thermal process can be
used to secure the elastic cover to the sheath. In some
embodiments, the elastic cover can be heat shrink tubing that is
applied over the expandable sheath, and heated to a temperature
high enough to cause the tubing to shrink around the sheath. In
some embodiments, a distal soft tip can then be attached to the
shaft of the expandable sheath.
In some embodiments, the outer layer can be co-extruded with an
adhesive layer, such as a layer formed from Tecoflex, such that the
Tecoflex is positioned on an inner surface of the outer layer--in
this manner the Tecoflex will be positioned between the inner and
outer layers in the completed sheath. In these embodiments, an HDPE
tube can be provided with a coating of Tecoflex on the inner
surface. The HDPE tube can be slit along the length of the tube to
open and flatten it, and then cut using a template in some
embodiments. For example, for specific applications, portions of
the outer layer can be cut and removed using a template. The cut
HDPE can then be placed on the inner layer on the mandrel. In some
embodiments, only a portion of the outer layer will have the
adhesive Tecoflex. In these embodiments, the sections without
Tecoflex will only be partially fused to the inner layer. In some
embodiments, the entire inner surface of the outer layer will have
the Tecoflex, and the inner surface of the outer layer can be
positioned so that it contacts the inner layer on the mandrel. To
position the inner and outer layers as shown in the sheath of FIG.
39, the folded portion of the inner layer can be lifted up, and an
edge of the outer layer can be tucked beneath the fold.
Sheaths of the present disclosure can be used with various methods
of introducing a prosthetic device into a patient's vasculature.
One such method comprises positioning an expandable sheath in a
patient's vessel, passing a device through the introducer sheath,
which causes a portion of the sheath surrounding the device to
expand and accommodate the profile of the device, and automatically
retracting the expanded portion of the sheath to its original size
after the device has passed through the expanded portion. In some
methods, the expandable sheath can be sutured to the patient's skin
at the insertion site so that once the sheath is inserted the
proper distance within the patient's vasculature, it does not move
once the implantable device starts to travel through the
sheath.
Disclosed embodiments of an expandable sheath can be used with
other delivery and minimally invasive surgical components, such as
an introducer and loader. In one embodiment, the expandable sheath
can be flushed to purge any air within the sheath, using, for
example, flush port 103 (FIG. 35). An introducer can be inserted
into the expandable sheath and the introducer/sheath combination
can be fully inserted into vasculature over a guiding device, such
as a 0.35'' guidewire. Preferably, the seam formed by the
intersection of the folded portion of the inner layer and the
overlapping portion of the outer layer can be positioned such it is
oriented downward (posterior). Once the sheath and introducer are
fully inserted into a patient's vasculature, in some embodiments,
the expandable sheath can be sutured in place at the insertion
site. In this manner, the expandable sheath can be substantially
prevented from moving once positioned within the patient.
The introducer can then be removed and a medical device, such as a
transcatheter heart valve can be inserted into the sheath, in some
instances using a loader. Such methods can additionally comprise
placing the tissue heart valve in a crimped state on the distal end
portion of an elongated delivery apparatus, and inserting the
elongated delivery device with the crimped valve into and through
the expandable sheath. Next, the delivery apparatus can be advanced
through the patient's vasculature to the treatment site, where the
valve can be implanted.
Typically, the medical device has a greater outer diameter than the
diameter of the sheath in its original configuration. The medical
device can be advanced through the expandable sheath towards the
implantation site, and the expandable sheath can locally expand to
accommodate the medical device as the device passes through. The
radial force exerted by the medical device can be sufficient to
locally expand the sheath to an expanded diameter (e.g., the
expanded configuration) just in the area where the medical device
is currently located. Once the medical device passes a particular
location of the sheath, the sheath can at least partially contract
to the smaller diameter of its original configuration. The
expandable sheath can thus be expanded without the use of
inflatable balloons or other dilators. Once the medical device is
implanted, the sheath and any sutures holding in place can be
removed. In some embodiments, it is preferable to remove the sheath
without rotating it.
In view of the many possible embodiments to which the principles of
the disclosed invention can be applied, it should be recognized
that the illustrated embodiments are only preferred examples of the
invention and should not be taken as limiting the scope of the
invention. Rather, the scope of the invention is defined by the
following claims. We therefore claim as our invention all that
comes within the scope and spirit of these claims.
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